[PEPPo] Helicity User's Guide

[Joseph Grames]

I have added the Helicity Board User's Guide to the PEPPo wiki:
https://positron.jlab.org/wiki/index.php/Run_Information

The guide is to help determine the meaning of the ~handful of parameters which set the helicity signal which goes to the beam and also to the DAQ. Note, the only possible difference between the two is the delay (HELDELAYd) which is the number of helicity windows (not pattern groups of helicity windows) the daq is delayed wrt to the beam.